Thread covering apparatus



March 17, 1942. I

I THREAD COVERING APPARATUS O. W. SCHLUMS Filed Aug. 15, 1940 INVENTOR.

Ofta WJckh/w'.

Patented Mar. 17, 1942 UNITED STATESPATENT OFFICE THREAD COVERINGAPPARATUS Otto W. Schl ums, Whitinsville, Mass.,-assignor to WhitinMachine Works, Whitinsvillc, Mass, a corporation of MassachusettsApplication August 15, 1940, Serial No. 352,783

3 Claims.

This invention relates to a method and apparatus for producing coveredrubber thread by winding one or more covering threads about a tensionedrubber core thread. In order to produce satisfactory covered rubberthread, it is necessary that the thread be under uniform tension whileit is being covered, so that uniform contraction may thereafter occur.

It is the general object of my present invention to provide'an improvedmethod and apparatus for winding orcovering a rubber thread undersubstantially uniform tension.

To .the attainment of this object, I provide means to produce apredetermined stretch in the rubber thread as it is being covered, and Ialso provide means to entirely relax the rubber thread before it is thusstretched and tensioned for the covering. operation. In this way, thepositively-actuated stretching or tensioning device will always producethe same tensioning result, which would not be the case if the rubberthreads were under varying initial tension before stretching.

More specifically, I provide means for entirely relaxing the tension inthe rubber core thread just before it enters the lower feed rolls of acovering machine.

My invention further relates to certain ordered I procedure and tocertain arrangements and combinations of parts which will be hereinafterdescribed and more particularly pointed out in the appended claims.

- A preferred form of the apparatus is shown 1 the drawing, in whichFig. 1 is a sectional. side elevation of thread covering apparatusembodying my improvements; I I

Fig. 2 is a detail front elevation, looking in the direction of thearrow 2 in Fig. 1; and

Fig. 3 is a similar view showing a slightly modifled construction.

Referring to Fig. 1, I have shown portions of a thread covering machineincluding a lower covering spindle l0 mounted on a fixed spindle railII, an upper covering spindle l2 mounted on a fixed spindle rail H, apair of lower feed rolls l5, and a pair ofupper feed rolls IS. Thespindles l0 and i2 are provided with tubular center posts which areaxially aligned and through which the rubber thread R isdrawn upward.The covering yarns Y and Y are sup plied fromspools S and S and theyarns are guided to the rubber thread R through rotatably mountedtravelers T and T. The upper feed rolls it are driven at a somewhathigher ripheral speed than the lower feed rolls l5, so that the rubberthread R is given a predetermined stretch between the lower and upperfeed rolls. As the thread is drawn upward, it first receives a windingof the yarn Y in one direction, and thereafter receives a secondwindingof the yarn Y. commonly in the opposite direction. The spindlesl0 and I! may be driven by belts I8 and I9 from any suitable source ofpower.

The parts thus far described are or may be of a usual commercialconstruction and in themselves form no part of my present invention,which relates particularly to improved means for feeding the rubberthread R to the feed rolls IS in a relaxed condition.

The thread R is commonly supplied on spools 20 having peripheral contactwith feed rolls 2| by which the thread is unwound. The thread R passesfrom the spool 20 to auxiliary feed rolls 30 which rotateat a slightlyfaster peripheral speed than the feed roll 2|, thus slightly tensioningthe thread R as it is drawn from the spool 20. This slight tension isdesirable to free the thread from the spool and to prevent catching orsnarling thereof.

The thread R, as wound on the spool, is

commonly under some initial tension and it is desirable that thistension be entirely relaxed before the thread entersthe feed rolls I5,as

the initial tension in the thread may not be unirelax the thread betweenthe feed rolls 30 and i the feed rolls l5 depends on the initial tensionin the thread on the spool 20, on the speed ratio between the 'roller 2|and the rolls l5, and. also on the pressure applied to the threadbetween the feed rolls l5. g t

It is found that feed roll pressure on a rubber thread produces a kindof negative draft, so that the length of thread delivered by the feedrolls is less than the theoretical delivery calculated 7 from theperipheral speed of the rolls.

This negative draft, plus the decrease in speed of the rolls I5 withreference to the roll 2|, should substantially, equal the percentage oforiginal tension in the thread on the spool 20, in order that the threadmay hang in a free loop and that the loop may not substantially gain orlose.

Pressure-adjusting means, such as a spring 30'.

and adjusting screw ll is provided by which the pressure of the rolls I!may beslightly varied tions and satisfactory high grade covered rubberthread is thereby produced.

In Fig. 3 I have shown a slight modification in which the rubber threadis supplied'in' packages P which are supported-on a continuous feed rollll. The operation is the same as previously described.

Having thus described my invention and the advantages thereof, I do notwish to be limited to the details herein disclosed, otherwise than asset forth in the claims, but what I claim is:

1. In a thread covering apparatus, means-to give a predetermined stretchto. a rubber thread, and means to impart a negative draft to the threadas it is delivered to said stretching means, said negative draft meansincluding feed rolls operating under yielding pressure, and saidnegative draft being in such amount that the initial tension in thethread is removed and that the thread is fully relaxed as it isdelivered to said stretching means.

2. The combination in thread covering apparatus as set forth in claim 1,in which means is provided to regulate the pressure of the feed rollsand thereby varythe negative draft.

3. In a thread covering apparatus, a roll to unwind tensioned rubberthread from a spool,

pressure rolls speeded to additionally tension the thread as it isunwound from the spool, feed rolls having less peripheral speed thansaid unwinding roll, means to apply pressure between said feed rolls,means to stretch the thread as it leaves the feed rolls and to maintainuniform stretch therein during the covering of the thread,

and means to winda covering thereon.

' o'rro w. scrum/rs.

